Doctors & patients are saying about ''...

" is a great web site for patients, that is unequaled by anything else out there."

Dr. Douglas L. Packer, MD, FHRS, Mayo Clinic, Rochester, MN

"Jill and I put you and your work in our prayers every night. What you do to help people through this [A-Fib] process is really incredible."

Jill and Steve Douglas, East Troy, WI 

“I really appreciate all the information on your website as it allows me to be a better informed patient and to know what questions to ask my EP. 

Faye Spencer, Boise, ID, April 2017

“I think your site has helped a lot of patients.”

Dr. Hugh G. Calkins, MD  Johns Hopkins,
Baltimore, MD

Doctors & patients are saying about 'Beat Your A-Fib'...

"If I had [your book] 10 years ago, it would have saved me 8 years of hell.”

Roy Salmon, Patient, A-Fib Free,
Adelaide, Australia

"This book is incredibly complete and easy-to-understand for anybody. I certainly recommend it for patients who want to know more about atrial fibrillation than what they will learn from doctors...."

Pierre Jaïs, M.D. Professor of Cardiology, Haut-Lévêque Hospital, Bordeaux, France

"Dear Steve, I saw a patient this morning with your book [in hand] and highlights throughout. She loves it and finds it very useful to help her in dealing with atrial fibrillation."

Dr. Wilber Su,
Cavanaugh Heart Center, 
Phoenix, AZ

"...masterful. You managed to combine an encyclopedic compilation of information with the simplicity of presentation that enhances the delivery of the information to the reader. This is not an easy thing to do, but you have been very, very successful at it."

Ira David Levin, heart patient, 
Rome, Italy

"Within the pages of Beat Your A-Fib, Dr. Steve Ryan, PhD, provides a comprehensive guide for persons seeking to find a cure for their Atrial Fibrillation."

Walter Kerwin, MD, Cedars-Sinai Medical Center, Los Angeles, CA

Stroke Risk

2021 AF Symposium Spotlight Session: Javelin VINE Filter to Prevent Stroke

2021 AF Symposium

Spotlight Session: Javelin VINE Filter to Prevent Stroke

Dr. Stuart Connolly

Dr. Stuart Connolly

Dr. Stuart Connolly of McMaster University in Hamilton, Ontario, Canada gave a 5-minute Spotlight Session talk on the Javelin Medical’s Filter to prevent stroke. Javelin Medical is an Israeli company located in Yokne’am Illit, Israel.

(Of all the 5-minute Spotlight Session talks, this is my personal favorite. Inserting the Javelin Filter can stop most clots from getting to the brain and causing a stroke. That’s incredibly good news for many A-Fib patients! It’s simple, ingenious, and very effective.)

Filtering Out Clots Before They Get to the Brain

The idea behind the Javelin Medical VINE filter is to catch clots (emboli) trying to travel up into the brain. This is done by inserting the VINE filter into both carotid arteries.

Insertion of the Javelin Medical VINE filter

Insertion of the Javelin Medical VINE filter using Ultrasound probe

How it works: The VINE filter is inserted under the skin using ultrasound and usually without need for general anesthesia. It is a super-elastic thread-like Nitinol filter. When it’s inserted, it expands into a helical shape that fills and blocks the carotid artery while still allowing for normal blood flow to the brain.

Any clots are caught in the dense cone-like filter. Over time these trapped clots dissolve due to normal blood flow through the filter. Internal and external anchors lock the filter in place inside the carotid arteries. The VINE is intended to last for a lifetime.

Diagram: Side view Javelin Medical VINE filter

Diagram: Side view Javelin Medical VINE filter

Preliminary Studies: In early studies with sheep, the VINE filter was successfully inserted and deployed with at least a 94% success rate.

Now in Phase II Trials

The VINE is now in preliminary Phase II trials (Capture II). There have been no adverse events. But it will probably take years to get U.S. FDA approval before it’s available.

Editor’s Comments

Even when taking anticoagulants, some A-Fib patients are still at risk of an ischemic stroke. The Javelin VINE Filter could change that. Insertion of the VINE would make it improbable for a clot to make its way through the carotid arteries to the brain.
Having this extra protection would  give A-Fib patients greater peace of mind.
For patients unsuitable for oral anticoagulants, development and approval of the Javelin VINE Filter could be life-changing.
Less Need for Anticoagulants? Can the Javelin VINE Filter eventually replace the need for A-Fib patients to take anticoagulants at all? That probably isn’t likely, at least not in the near future. (Clots may still reach the brain through the vertebral arteries.) But imagine a time when no one would ever have to take anticoagulants!
Public Health Implications Beyond A-Fib: Could the Javelin Filter be used, not just in A-Fib patients, but in anyone at risk of stroke? According to Dr. Connolly, over 800,000 people a year suffer a stroke, 1 out of 3 of those due to A-Fib.
Major Healthcare Break Through? Can we dream of a world where anyone reaching, for example, age 65 would go in for a simple procedure that would forever protect them from having a clot or stroke?

The Javelin VINE Filter may make this possible. It may become a major breakthrough in health care.

Added 4/28/21: Please be advised that the above Editor’s Comments are probably way too optimistic at this time. These are very early days in the research and development of the Javelin filter. We need more data. It hasn’t been proven safe yet, let alone effective.

If you find any errors on this page, email us. Y Last updated: Wednesday, April 28, 2021

Return to 2021 AF Symposium Reports

Insertable Cardiac Monitor (ICM) to Prevent Recurrent Stroke

The CRYSTAL-AF randomized control trial looked at patients who had a cryptogenic stroke (e.g., a stroke with no identifiable cause). These strokes, 20-40% of cases, account for nearly 175,000 ischemic (blocked artery in the brain) strokes every year in the U.S. (American Stroke Association).

This type of stroke i.e., undetected, can be caused by Silent Atrial Fibrillation.

In this study, patients received an Insertable Cardiac Monitor (ICM), such as the Medtronic Reveal LINQ loop recorder, to detect A-Fib. It’s inserted under the skin and works 24/7 for three years. [I have one. It’s very small and not noticeable.]

By detecting silent A-Fib, ICMs lower the risk of a patient having a second stroke.

Nine-Fold Higher A-Fib Detection Rate

The CRYSTAL-AF study found that using ICMs provided a nine-fold higher A-Fib detection rate compared with the standard treatment (e.g.: intermittent ECG and Holter monitoring).

Medtronic Reveal LINQ insertable heart monitor

Insertable Cardiac Monitor (ICM) from Medtronic 

This finding led many patients who had experienced a stroke of unknown cause (cryptogenic), to start taking anticoagulants. [Truth be told, most people who have a stroke and survive it are put on anticoagulants or antiplatelets and don’t have to be motivated to take them.] 

A similar study using the Zio monitor, iRhythm Technologies, Inc., found similar results. While wear time in the study with the Zio patch was up to 4 weeks, an ICM lasts for 2-3 years.

ICMs Improve Quality of Life and People Live Longer

In the CRYSTAL-AF study comparing immediate ICM use versus standard treatment of intermittent ECG and Holter monitoring. Patients showed a benefit in quality-adjusted life-year (QALY) of 0.198 and an improvement of 0.226 in life years.

The Quality-Adjusted Life Year (QALY) is a measure of the value and benefit of health outcomes.

The ICM approach was projected to lead to 60 fewer lifetime ischemic strokes per 1,000 patients. And ICM was shown to be a cost-effective monitoring strategy.

A-Fib Stoke: Higher Risk if Age 65+

If you have an A-Fib stroke and survive, you have about a 50% higher risk of remaining disabled or handicapped (compared to stoke patients without A Fib).

MRIs often show permanent lesions on the brain from the stroke, even if the patient recovers.

All too many people 65+ have a stroke of unknown cause. Only after they have a stroke and survive it, do they find out they had “silent” A-Fib, and that it probably caused their stroke. But obviously, at that point, that’s too late.

CRYSTAL-AF: Find A-Fib Before a Second Stroke

From a public health standpoint, the CRYSTAL-AF study highlights the need to check if a stroke patient has Atrial Fibrillation and treat in time to prevent a second stroke.

“Atrial fibrillation after cryptogenic stroke [of undetermined source] was most often asymptomatic and paroxysmal and thus unlikely to be detected by strategies based on symptom-driven monitoring or intermittent short-term recordings.” -Sanna, et al. NEJM

Editor’s Comments

Editor's Comments about Cecelia's A-Fib story

Danger of Anticoagulants: The CRYSTAL-AF model assumes that all patients would start taking a NOAC ( anticoagulant) once A-Fib is diagnosed.
But should everyone over 65 with silent A-Fib be on anticoagulants? Remember: anticoagulants are high risk drugs and can cause problems such as hemorrhagic strokes. i.e. bleeding in the brain. (See High Hemorrhagic Risk Factors from NOACs and Anticoagulants Increase Risk of Hemorrhagic-Type Strokes.)
Options for A-Fib Stroke Prevention: Beyond Drug Therapy. A-Fib patients have several options to prevent A-Fib strokes rather than having to take anticoagulants (NOACs).
A-Fib patients have several options to prevent A-Fib strokes rather than having to take anticoagulants (NOACs).
The most obvious one is to become A-Fib free through a catheter ablation. You can’t have an A-Fib stroke if you no longer have A-Fib.
Another option is to close off or cut out the Left Atrial Appendage (LAA) where most A-Fib clots originate (strategies include the Watchman device or AtriClip heart surgery).
A third option is natural blood thinners such as Nattokinase, even though they haven’t been tested as much as NOACs.
ICMs Detect Silent A-Fib and Save Lives: Insertable Cardiac Monitors (ICMs) can tell doctors (and patients) if someone has “silent” A-Fib, i.e. without any apparent symptoms. Silent A-Fib accounts for 20%-40% of strokes.
Could lives be saved and brain damage avoided if everyone reaching age 65 could be given an ICM? 
How many people over age 65 have silent A-Fib? How many lives could be saved and brain damage avoided if everyone reaching age 65 could be given an ICM? ICMs aren’t very expensive, especially when one considers the alternative.

From a public health standpoint, we need a concerted effort to educate doctors and patients on the dangers of silent A-Fib strokes and how to reduce the risk.

The Routine EKG May Not be Enough: Compared to getting a routine EKG at your doctor’s office, ICMs are much more effective at detecting silent A-Fib. Perhaps consumer devices like the Apple Watch can provide this same info.

Resources for this article

• Steinhubl SR, et al. Effect of a Home-Based Wearable Continuous ECG Monitoring Patch on Detection of Undiagnosed Atrial Fibrillation: The mSToPS Randomized Clinical Trial. JAMA. 2018;320(2):146–155. doi:10.1001/jama.2018.8102

• SCREEN-AF study results published in JAMA Cardiology, Cardiac Rhythm News. March 3, 2021.

• Sanna T, et al. Cryptogenic Stroke and Underlying Atrial Fibrillation (CRYSTAL AF). N Engl J Med. 2014; 370(26):2478-2486

• Sinha, A. et al. Cryptogenic Stroke and underlying Atrial Fibrillation (CRYSTAL AF): design and rationale DOI: 10.1016/j.ahj.2010.03.032

Finding the Right Doctor for You and Your A-Fib

by Steve S. Ryan, Last updated: August 24, 2020

When your family doctor first suspects you have A-Fib, they will probably send you to a cardiologist, a doctor who specializes in the heart.

The cardiologist will want to put you on different medications (called Drug Therapy) over the next six months to a year or more to see if any of these medications will stop or control your A-Fib. 

But current A-Fib medications are not very effective. They work for only about 40% of patients and frequently stop working over time. Many people can’t tolerate the bad side effects.

Know that time is of the essence in treating A-Fib. The longer you have A-Fib, the more your A-Fib may “remodel” your heart (i.e. change it physically and electrically). Read Dr. Oussama Wazni’s advice about drug therapy:

“…Once the diagnosis of atrial fibrillation is made, it’s important not to spend too much time trying to keep a patient in normal rhythm with medical (drug) therapy…before referring them to catheter ablation.”  

– Dr. Oussama Wazni, Co-Director of the Center for Atrial Fibrillation at the Cleveland Clinic

 How to Start Your Search

To seek treatments beyond medications, you may need to change doctors.

Since Atrial Fibrillation is an electrical problem, you should see a Cardiac Electrophysiologist (EP)a cardiologist who specializes in the electrical activity of the heart and in the diagnosis and treatment of heart rhythm disorders.

A-Fib is an electrical problem. Patients should see an Electrophysiologist, an EP, a cardiologist who specializes in the electrical activity of the heart.

The EP’s primary concern is creating a ‘treatment plan’—an organized path to finding your A-Fib cure or best outcome.

To find the right doctor for you, seek recommendations from your General Practitioner (GP) and from other A-Fib patients (see Resources/Bulletin Boards for a list of online discussion groups).

If you know nurses or support staff who work in the cardiology field or in Electrophysiology (EP) labs, they can be great resources.

When you go to A-Fib centers with several EPs, be aware that the office will tend to assign you to the newest, least experienced EP on staff. You should instead do your research first and ask for a particular EP you know is more experienced; for example, someone with the initials FHRS after his name or a Castle Connolly Top Doctor.

Finding a Heart Rhythm Specialist’ Online

To find a local Electrophysiologist yourself, we recommend the Heart Rhythm Society website and their feature called Finding a Heart Rhythm Specialist’. ‘Check’ the box “to limit the results to Fellows of the Heart Rhythm Society (FHRS)”. (EPs with the FHRS designation have been recognized by their peers and are experienced heart rhythm professionals working in the field of electrophysiology and/or pacing).

When you type in a U.S. city and state (or country), the site gives you a list of Electrophysiologists in your area. Check for their list of specialties (not all EPs perform catheter ablations, for example; some focus on pacing/pacemakers, or clinical research, etc.). Look for additional information such as which medical insurance they accept.

 Our Directory

This Directory of Doctors and Facilities is an evolving list of the physicians and medical centers who treat patients with atrial fibrillation. Our directory is offered as a service and convenience to A-Fib patients. It’s divided into sections:

U.S. Doctors and Centers by state/city
International listings by country or geographic region.
• Steve’s Lists’ of doctors by specialty.

 Organize Your Research

To find the right doctor to cure your A-Fib, start your research with a notebook and a three-ring binder or a file folder. Learn Why You Need an A-Fib Notebook and 3-Ring Binder.

You need to organize the information you will be collecting: printouts of information from the internet, copies of documents from your local public library or medical center library, notes from phone calls, and answers to “interview” questions during doctor consultations.

Your 3-ring binder, or file folder is also where to collect copies of all your lab tests, notes from doctor visits, doctor correspondence, etc.

Obtain Copies of Your Medical Records, Tests, and Images

If you need to request copies of some medical records, read our article, How to Request Copies of your Medical Records. We give you three ways to request your medical records from your doctors and healthcare providers.

Later, when you are ready to interview new doctors, you will want to send each office a packet with your medical records, test results, and images or X-rays. (As a back-up, bring your three-ring binder with the originals.)

We strongly encourage you to get in the habit of keeping a copy of every test result you get in a designated three-ring binder.

Don’t leave your doctor’s office or hospital without a copy of every test they perform. Or if the test result isn’t immediately available, have them mail it to you.

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 Researching Doctors and Centers

Don’t rely on a single online source when researching and selecting doctors. Be cautious of all doctor informational listings you find on web sites (yes, including this one).

Doctors may be listed or appear most prominently because they pay for that privilege (but not so at Read my article, Don’t be Fooled by Pay-to-Play Online Doctor Referral Sites.

Don’t depend on websites of patient’ ratings of doctors or with patient surveys. They lend themselves to manipulation. Ratings often reflect how well-liked a doctor is, not competency. Consult several sites.

 How to Find the Information

You must do your own homework. To narrow down your list of prospective doctors you will want to scrutinize their credentials. To research each doctor, consult the internet or your local library. One or more of the following online resources may be helpful.

Credential Acronyms: For an explanation of the acronyms following a physician’s name, see Physician Credentials.

The Heart Rhythm Society ‘Find a Specialist searchable directory for a doctor’s specialties, insurance accepted, etc.;
The American Board of Medical Specialists (ABMS) Directory of Board Certified Medical Specialists;
The American Board of Internal Medicine; Check a doctor’s certification;
Vitals, an independent healthcare ratings organization; provides physician’s profile, education, awards & recognition, insurance accepted, hospital affiliations, and info on malpractice and sanctions.

 Your Consultation Appointments

Narrow down your list to the top three doctors. Now you are ready to set up a consultation appointment with each doctor. Think of this as an interview. Don’t worry, doctors are also ‘interviewing’ you to determine if they can help you. What to say:

1. You have Atrial Fibrillation, and what kind (paroxysmal, persistent or long-standing persistent);

2. You want to consult with the doctor about your treatment goals, for example, you are seeking to cure your A-Fib, not just manage it with drugs.

Note: some EPs have a “referrals only” policy, which means they won’t talk to you directly. You have to be referred by a cardiologist or a family doctor.

Send Your Medical Records Beforehand

Before your appointment, send each doctor a packet with your A-Fib-related medical records. To learn what to include in your packet of medical records, read Why You Need an A-Fib Notebook and 3-Ring Binder and Your Personal A-Fib Medical Summary.

Download our worksheet

Questions to Ask: Use Our Free Worksheet

To help you scrutinize prospective doctors, we’ve written a set of 10 interview questions to help get you started. Download the FREE PDF and save to your hard drive. Then, print a worksheet for each doctor you interview. 

(To ‘interpret’ the doctors’ answers on the worksheet, see our article, “Choosing the Right Doctor: 10 Questions You’ve Got to Ask And What Their Answers Mean“.)

Prepare and add your own list of questions for each prospective doctor.

During Your “Interview”

Never see a doctor alone...carry pen & paper and take lots of notes; A-Fib.comWhen you arrive at the doctors offices’, make sure they have indeed received your medical records. (As a back-up, bring your own originals from your three-ring A-Fib binder.)

Be sure you have your worksheets and list of other questions, a notepad and pen to take lots of notes.

Audio Recording: In addition, consider using an audio recorder to help you remember things. (Most doctors don’t mind, but always ask permission beforehand.) Many cell phones can be used to make a recording.

Take Along a Trusted Friend: You may want to take along a trusted friend or family member. As needed, your ‘personal advocate’ can question the doctor for you and verify your list of questions have been answered. It’s hard to be on top of your game when you feel ill and anxious. Studies show that patients immediately forget up to 80% of what’s discussed during a doctor visit, and get about half of the remainder wrong.

Afterwards, your patient advocate friend can help you evaluate the doctor’s answers, discuss anything that’s unclear and comment on the doctor’s demeanor.

To intrepret the doctor’s answers, see our article, “Choosing the Right Doctor: 10 Questions You’ve Got to Ask And What Their Answers Mean.

Afterwards: How to Interpret the Answers You Received

Back home, study your notes about each doctor. To ‘interpret’ the doctors’ answers, see our article, “Choosing the Right Doctor: 10 Questions You’ve Got to Ask (And What Their Answers Mean)“.  We’ve included the various responses you might receive, and what each response means to you when searching for the right doctor for you and your treatment goals.

Also Assess the Doctor’s Manner and Personality

Warning - cautionYou’ll also want to assess the doctor’s manner and personality. Is this someone who will work with you? Someone who listens to how A-Fib makes you feel? If the doctor has an accent, are they still clear, concise and communicate well? Does this doctor inspire confidence? Are they encouraging and supportive? Is this someone you feel comfortable with and trust with your health care?

Your relationship with your doctor is important. See our post: ‘Do you Like’ Your Doctor, Do You ‘Connect’?…How it Affects Your Health

Rudeness, bad temper, boorish behavior, etc. from a doctor, no matter how highly recommended, should be a red flag for you. That kind of behavior is not just personally offensive but can be dangerous for your health.

Gender bias: Does he/she respect you? Women in particular should be wary of condescending behavior. ReadIt’s All In Your Mind” Her MD Said. Women in the US often don’t receive the proper diagnosis and treatment of their A-Fib.

To read more about gender bias by doctors, see “The Facts About Women with A-Fib: Mother Nature and Gender Bias—Or—Get Thee to an EP ASAP

Does the poor behavior also extend to how the doctor treats his staff? Patients of doctors “who don’t show respect for their medical staff have much higher rates of adverse effects, than patients of their more congenial colleagues,” according to Gerald B. Hickson, MD of Vanderbilt University Medical Center.

If your doctor is condescending or dismisses your concerns, you’re getting poor care. If a doctor is too busy to talk with you and answer your concerns, he’s probably too busy to take care of you properly.

But do give the doctor a break. They may be having a bad day or may have heard your questions too many times before. So say something, speak up! Or contact the patient-relations representative at the medical center. They want to know if a doctor is rude (those patients are more likely to sue!). Once a doctor’s bad behavior is called to his attention, they are likely to do better. And you’ll feel better, too.

 Evaluate the Consultations

After seeing your top three doctors, compare their answers. Did one doctor stand out?  If not, you may want to go back to your research list for number four and five on your list and set up appointments with them too.)

 Directory of Doctors & Medical Centers

The Directory of Doctors lists US & international physicians and medical centers treating Atrial Fibrillation patients. This evolving list is offered as a service and convenience to A-Fib patients. (Unlike other directories, we accept no fee to be included.) The directory is divided into three categories.

US Doctors and Medical Centers (by state/city)
International: Doctors and Medical Centers (by country or region)

For a list of EPs doing Catheter Ablation procedures, see Steve’s Lists/US EPs with FHRS-designation performing A-Fib ablations by US State/City.

 For surgeons performing Maze/Mini-Maze operations, see Doctors & Facilities/Steve’s Lists Doctors by Specialties and more specifically, US Surgeons performing Maze and Mini-Maze operations.

Resources for this article

• Shannonhouse, R. “Is Your Doctor a Bully?” Bottom Line Health, September 2013, p. 2.

• Fellowship in the Heart Rhythm Society (FHRS) Information. Heart Rhythm Society website. Accessed April 8, 2014. URL:

• Makary, Marty. “7 Things Your Hospital Won’t Tell You (That Could Hurt You)” Bottom Line Personal, Volume 34, Number 2, January 15, 2013. p1.

• Hussein, AA, et al. Radiofrequency Ablation of Persistent Atrial Fibrillation: Diagnosis-to-Ablation Time, Markers of Pathways of Atrial Remodeling, and Outcomes. Circulation: Arrhythmia and Electrophysiology. 2016;9:e003669.

• McDaniel, Susan H. The Right Way to Ask Your Doctor Questions. Bottom Line Health. Volume 31, Number 4, April 2017, p. 14.

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If you find any errors on this page, email us. Y Last updated: Monday, August 24, 2020  

Video: Atrial Fibrillation-Clot Formation & Stroke Risks

In atrial fibrillation AFib, or AF, the most common abnormality of the heart’s rhythm, the atria contract in a rapid and disorganized way. As a result, the atria do not effectively pump blood into the ventricles.

Animation showing how A-Fib clots can form and travel to the brain causing an ischemic stroke. (1:39) Uploaded to YouTube on Jan 4, 2012 by Thrombosis Adviser.

YouTube video playback controls: When watching this video, you have several playback options. The following controls are located in the lower right portion of the frame: Turn on closed captions, Settings (speed/quality), Watch on YouTube website, and Enlarge video to full frame. Click on arrow  icon to select.

If you find any errors on this page, email us. Y Last updated: Friday, August 21, 2020

Return to Instructional A-Fib Videos and Animations

2020 AF Symposium Abstract: High Hemorrhagic Risk Factors from NOACs

2020 AF Symposium Abstract

High Hemorrhagic Risk Factors from NOACs

by Steve S. Ryan

VIDEO A-Fib Clot Formation & Stroke Risks

NOAC Hemorrhagic Stroke Risk

When I read in this abstract from Massachusetts General Hospital in Boston, these NOAC findings almost jumped off the page at me! We know that NOACs are high risk meds (though they are certainly better than having an A-Fib stroke). But, add to that, also a high risk of Hemorrhagic risk factors, too?

This is a most important and relevant study for A-Fib patients.

Brain MRI to Detect NOAC Hemorrhagic Stroke Risk

Researchers from Massachusetts General Hospital in Boston used MRI to identify markers of increased intracerebral hemorrhage risk (ICH).

This was a single center study conducted from January 2011 to May 2019. In the study were 282 patients of which 76% had Atrial Fibrillation; Of the 282 patients, 49 were taking NOACs and 233 were taking warfarin. All demographic variables, vascular risk factors, etc. were similar between the two groups.

Study Findings

Analyzing the MRI data of the 282 participants revealed:

• cerebral microbleeds (67%)
• moderate-to-severe white matter hyperintensities (76%)
• cortical superficial siderosis (excess iron in body tissue) (18%)

In particular, of the 49 patients taking NOACs:

• 97% had at least one of these markers
• 60% had two
• 4% had all three


Established MRI markers of increased ICH (intracerebral hemorrhage) were common in the NOAC study group.

High hemorrhagic risk markers were present in an overwhelming 97% of NOAC patients.

Editor’s Comments:

Does taking a NOAC long-term mean you’ll eventually develop a hemorrhagic stroke?
No, the researchers didn’t go that far. This was a limited study as the number of patients who were on NOACs was 49 compared to those on warfarin which was 233.
Red Flag Warning: But this study should raise a red flag for anyone taking NOACs long term. Almost all patients on NOACs (97% in this study) had “evidence of neuroimaging markers of high ICH risk.”
The authors recommended that prescribers (and patients) look at nonpharmacological stroke prevention methods. Eliminating the need for lifelong NOAC anticoagulation “may decrease the incidence of fatal/disabling hemorrhages in A-Fib patients.”

For more on NOACs and stroke, see my article Anticoagulants Increase Risk of Hemorrhagic-Type Strokes.

Das, A.S et al. Etiology and Imaging Risk Markers of Non-Vitamin K Antagonist Oral Anticoagulant-Related Intracerebral Hemorrhage. AFS2020-17. AF Symposium 2020 brochure, p. 42.

If you find any errors on this page, email us. Y Last updated: Friday, January 22, 2021

Return to 2020 AF Symposium Reports

2020 AF Symposium: Device-Detected A-Fib and Stroke Risk

AF Symposium 2020

Device-Detected A-Fib and Stroke Risk: How Long For a Clot to Form?

by Steve S. Ryan

Daniel Singer MD

How long does it take for a clot/stroke to develop? Dr. Daniel Singer from Massachusetts General Hospital in Boston, MA addressed this most important question both for A-Fib patients and their doctors in his AF Symposium presentation― Update on Device-Detected AF and Stroke Risk as a Function of AF Burden-Clinical Implications.” 

Implanted Devices Help Study Clot Formation

Dr. Singer discussed how implanted rhythm devices such as pacemakers have aided Electrophysiologists (EPs) collect data on clot formation timelines. (Mobile and non-implanted devices such as the Kardia or Apple Watch may open up these studies to a much broader population.)

AF detection devices: minimally invasive devices to permanent implanted devices; source: AHA

Read: How Clots Form and Cause Strokes
When someone is in A-Fib, blood is not being effectively pumped out of the left atrium. This blood can collect in areas such as the Left Atrial Appendage (LAA) where a pool of blood can form a clot.

When the left atrium starts beating in normal sinus rhythm again, this clot can be pushed downstream into the left ventricle which then pumps this clot into the brain causing an ischemic stroke.

But these clots aren’t formed instantaneously. It takes a while for blood to pool and clot to a significant size. For example, if you have a ten-minute attack of A-Fib, it’s unlikely a clot/stroke will develop.

In cases of permanent A-Fib, normal sinus rhythm doesn’t need to return to move the clot into the ventricle and from there to the brain. This makes patients in permanent A-Fib at high stroke risk.

The ASSERT Study: How Long Does It Take for a Clot to Form?

Dr. Singer discussed the ASSERT study (the Asymptomatic Atrial Fibrillation and Stroke Evaluation in Pacemaker Patients and the Atrial Fibrillation Reduction Atrial Pacing Trial).

The study enrolled 2,580 patients, 65 years of age or older, with hypertension and no history of A-Fib, in whom a pacemaker or defibrillator (ICD) had recently been installed.

Detecting Silent A-Fib: The pacemaker and ICD devices were programmed to detect silent A-Fib (Subclinical Atrial Tachycardia [SCAF]) when the heart rate reached 190 beats or more per minute lasting more than 6 minutes.

Silent A-Fib is called Subclinical Atrial Tachycardia (SCAF). Different from clinical A-Fib, it’s often of short duration and often is asymptomatic.

The devices were checked at a clinical visit 3 months later. These patients were then followed up for around 2.5 years.

ASSERT Study Result: They found that it took more than 17.72 hours to significantly increase annual stroke risk.

The ASSERT study basically said that it takes around 24 hours of silent A-Fib (SCAF) to develop a serious risk of stroke. Patients with silent A-Fib for over 24 hours had around a 3.1% risk of developing a clot/stroke.

In a later analysis of the ASSERT study by Van Gelder (2017), patients with a SCAF of from 6 hrs to 24 hrs were not significantly different from patients without SCAF.

TRENDS Study, A-Fib and Stroke Risk

Using much the same implanted device strategies as in the ASSERT study, the TRENDS study enrolled patients (2,486) with one or more stroke risk factors. They used a 30-day window to measure silent A-Fib (AT/AF burden).

Ischemic stroke is the most common type of stroke for A-Fib patients.

Findings: Having silent A-Fib for 5.5 hours or more on any 30-day window appeared to double stroke risk (12% of patients in the study had a stroke). (Stroke rates in this study were far below the 4% anticipated annual rate.)

A-Fib Cause or Marker of Stroke Risk? In the TRENDS study (and in the ASSERT study) nearly ¾ of the patients didn’t have A-Fib before the study. This raises the issue of whether A-Fib causes or is just a marker for stroke risk.

Silent A-Fib Hard to Detect

In the ASSERT study, the median time to detect silent A-Fib within the first 3 months was 36 days.

For many patients, just getting an ECG in your doctor’s office or wearing a standard monitor for a few days may not detect if you have silent A-Fib.

This is a major public health issue.

The ASSERT study raises the possibility that patients who suffer ischemic strokes may have silent A-Fib. For those who had an A-Fib-associated stroke, 25% had their A-Fib detected at the time of the stroke. A-Fib-associated strokes account for about 20% of all ischemic strokes.

Unfortunately, from a public health perspective, longer-term monitors like the Medtronic Reveal LINQ (which lasts 3 years) are currently too expensive for screening the general population. Wearable or hand-held ECG monitors may ultimately fill this need.

Pacemakers Don’t Work to Prevent A-Fib

Another finding of the ASSERT study is that pacemakers (continuous overdrive pacing) “does not prevent clinical atrial fibrillation” episodes. (This was the primary question the ASSERT study was constructed to answer.)

Low CHA2DS-VASc and A-Fib Stroke Risk

Dr. Singer pointed out that, even with a high AF burden, there isn’t much stroke risk if the CHA2DS-VASc score is low.

He acknowledged that most Symposium attendees would probably consider that a 1-2-hour episode of silent A-Fib would be a risk factor for stroke.

While others would consider any A-Fib at all as requiring that the patient be put on anticoagulants.

Limitations of the ASSERT Study

The ASSERT study was not designed to study how long it takes for a clot/stroke to form.

The cut-off point at >17.72 hours is somewhat arbitrary. How many patients had strokes from 17.42 hours to 24 hours or 48 hours? What is the precise number of hours in A-Fib where the risk of stroke significantly increases?

ASSERT and TRENDS studied patients with pacemakers and defibrillators. These patients may have other heart problems that the average A-Fib patient doesn’t have.

Editor’s Comments:

Silent A-Fib (Subclinical Atrial Tachycardia [SCAF]) is really dangerous! This is an important public health issue.
I advocate everyone reaching age 65 have long-term monitoring for silent A-Fib. How many strokes could be prevented and lives saved simply by detecting silent A-Fib before it kills or disables people?
Silent A-Fib Is Dangerous―Get Tested at Age 65! If you are 65 or older, get tested for silent A-Fib. In the ASSERT study it took 36 days of monitoring to detect silent A-Fib (SCAF).
However, we don’t currently have rigorous trial evidence that such screening for A-Fib leads to lower stroke risk. The U.S. Preventive Services Task Force doesn’t yet recommend wide scale screening for A-Fib.
Shorter Episodes of A-Fib Not Generally Dangerous: Despite studies such as ASSERT and TRENDS, we still need many more studies on how long it takes for a clot/stroke to form. Probably the most useful data to date comes from the ASSERT study stroke risk where it took around 24 hours of silent A-Fib before clot/stroke risk was significantly increased.
Should All A-Fib Patients be on Anticoagulants? Patients with shorter episodes of A-Fib or those who develop A-Fib after a successful catheter ablation, may not need to be on anticoagulants at all.

Remember that anticoagulants are high risk drugs that shouldn’t be taken unless there is a real risk of stroke.

Hemorrhagic stroke: Another risk of A-Fib is a hemorrhagic stroke where blood bleeds/flows into the brain. For more, see my article, Anticoagulants Increase Risk of Hemorrhagic-Type Strokes

References for this report
Healey, J.S. et al. Subclinical Atrial Fibrillation and the Risk of Stroke. The New England Journal of Medicine 2012; 366:120-129.

Gotto, Jr., Antonio M. Bottom Line Health, Vol 26, November 2012, p. 4.

Van Gelder, I.C. et al. Duration of device-detected subclinical atrial fibrillation and occurrence of stroke in ASSERT. European Heart Journal, Volume 38, Issue 17. 1 May 2017, Pages 1339-1344,

If you find any errors on this page, email us. Y Last updated: Monday, January 18, 2021

Return to 2020 AF Symposium Reports

Can One Have a Stroke If A-Fib Free? Years After Successful Ablation, He has TIAs

Steve from Minnesota had a successful catheter ablation in 2016 at the Mayo Clinic. He remained in normal sinus rhythm (NSR), off all medications and felt very good. He walked every day and felt well.

TIA symptoms are the same as a stroke, and usually begin suddenly. The difference is the symptoms only last for a few minutes or hours as the blockage is temporary.

Recently he wrote to me that in the fall of 2018, he had a TIA (Transient Ischemic Attack, a temporary stroke) where his left arm went limp for about 30-60 seconds. Then in March 2019, another TIA caused him to lose complete vision in his left eye for 2-3 minutes.

In response, his electrophysiologist (EP) put him on the anticoagulant Eliquis. He wore a loop monitor which showed he was in normal sinus rhythm with only a single “5-beat atrial tachycardia” (only one irregular beat). All the usual tests came back showing no heart problems.

How can Steve have TIAs if he doesn’t have any A-Fib?

Unfortunately for A-Fib patients, clots and stroke can also be non-A-Fib related, such as vascular strokes or hypertensive lacunar stroke. (Vascular and cerebrovascular disease can produce a heart attack or coronary event as well as a clot or stroke.)

With A-Fib patients, clots more often come the Left Atrium and Left Atrial Appendage (LAA). But stroke can originate from other areas. For example, plaque deposits in the arteries can break loose and form clots.

Also, if Minnesota Steve developed some fibrosis while he was in A-Fib, his left atrium may not be contracting properly making clot formation more possible. And sometimes if the LAA is electrically isolated during the ablation, it may not be contracting properly and can develop clots.

(Doctors may want to check Minnesota Steve for Patent Foramen Ovale and Atrial Septal Defect where a hole in the septum can permit clots to pass to the brain. Though, normally, this problem would have been found when performing Steve’s original ablation.

A transient ischemic attack (TIA) occurs when part of the brain experiences a temporary lack of blood flow. This causes stroke-like symptoms that resolve within 24 hours. Unlike a stroke, a ministroke on its own doesn’t cause permanent disabilities.

Would a Watchman device to close off the LAA prevent these TIAs?

Not necessarily. For patients with A-Fib, clots tend to form in the Left Atrial Appendage (LAA) because blood tends to stagnate there. But if blood is being pumped properly in the left atrium, it’s harder for clots to form in the LAA. (And other areas of clot formation can occur in the left atrium besides the LAA.)

What should Steve do now? What can he do to guarantee that he will never have a stroke?

Having TIAs is a warning sign. Often, but not always, TIAs precede a major stroke. To help guard against clots and stroke, Minnesota Steve will likely have to be on an anticoagulant, such as Eliquis, for life.

What’s Next for Steve?

Minnesota Steve and his doctor should concentrate on treating vascular risk factors such as blood pressure, diabetes, cholesterol control, (CHADs2-VASc) and if needed, stop smoking. And, of course, continue monitoring for A-Fib.

Fibrosis makes the heart stiff, less flexible and weak, overworks the heart and reduces pumping efficiency.

Minnesota Steve probably should have an MRI done to measure for fibrosis in his heart. In addition, his Left Atrial Appendage (LAA) should be checked with a echocardiograph (TEE) to see if it is emptying properly.

His doctor may also want to determine how much plaque Minnesota Steve has in his arteries. How likely is it to break off and form clots? (Some doctors may suggest antiplatelet therapy in addition to the anticoagulant Eliquis, but usually the two are not combined effectively.)

I’ll continue to track Minnesota Steve’s progress and write an update if I get more information on his health status.

No Absolute Guarantee Against Stroke

While anticoagulants significantly lower the risk of an A-Fib stroke, they but do not totally eliminate it.

While anticoagulants significantly lower the risk of an A-Fib stroke, but they do not totally eliminate the risk.

A close friend of ours with A-Fib was on Coumadin at the ideal INR range (2.5) and still had a major stroke.

After a successful catheter ablation such as Minnesota Steve had, one’s stroke risk generally drops down to that of a normal person. But normal people have strokes and TIAs, too.

There is no therapy that will absolutely guarantee one will never have a stroke.

Share Your Views at A-Fib.comMinnesota Steve is blessed to have no permanent damage from those TIAs. But they are warning signs which must be heeded, probably by life-long anticoagulation. No one wants to be on anticoagulants for life. But he may not have any other choice.

Share your insights: Without a lot of current definitive research, this is a difficult subject to discuss. If anyone has any suggestions, criticisms, or comments to share on this most important topic, please email me.

A special thanks to Steve from Minnesota for asking this question and sharing his TIA experiences.

Your Nearest ‘Certified Stroke Center’ Could Save Your Life

or avert the debilitating effects of an A-Fib stroke.
But only if you get there within four hours.

Use my article to find your nearest certified or ‘Advanced Comprehensive Stroke Center’. Read my article.

The Watchman Occlusion Device and Risk of Device-Related Blood Clot

The Watchman is an occlusion device that closes off the Left Atrial Appendage (LAA) to prevent clots from getting into the heart. For those with A-Fib, 90%–95% of clots and strokes come from the LAA.

The Watchman device is considered an alternative or an improvement to a lifetime of taking anticoagulants including warfarin and the NOACs. See Watchman Alternative to Coumadin and Watchman Better Than Warfarin.

2018 HRS Report: Clots Can Form on the Watchman

A new meta-analysis of clinical trials and registries of the Watchman device is believed to be the largest to date of Device-Related Thrombi (blood clot) following left atrial appendage closure.

Size comparison of the Watchman occlusion device

The study shows that in about 3.7 percent of patients a blood clot forms on a metal screw on the face of the device. The clot can form many months, even a year after installation.

“While not frequent, when present, thrombus on the face of an LAA occluder is associated with a high rate of ischemic stroke,” said study presenter Vivek Y. Reddy of Mount Sinai Hospital in New York City. (Dr. Reddy was one of the original investigators of the Watchman clinical trials.) These findings were presented at the 2018 Heart Rhythm Society meeting.

Device-related thrombi (DRTs) are troublesome because they increase the risk of ischemic stroke by over 3 fold. However, no significant association with mortality emerged.

This risk, Dr. Reddy said, calls for aggressive management of patients at risk for device-related blood clots.

The Study: Finds Device-Related Thrombi (DRTs)

To better understand the mechanism of stroke after LAA closure, Dr. Vivek Reddy and his colleagues, looked at the incidence, predictors and clinical outcomes of device-related thrombus (DRT).

Watchman device: inserted (L) and progression of proper tissue growth (R)

The meta-analysis study looked at data on 1,739 patients who were successfully implanted with the Watchman device as part of four prior clinical studies. Patient follow-ups included a transesophageal echocardiography (TEE).

Findings: Among those patients receiving a Watchman, the investigators found 65 patients (3.74%) had DRT. Most were detected after anticoagulation had been discontinued at 45 days post-insertion. Some DRTs first showed up at the 1-year TEE.

“A majority of Watchman patients with an identified DRT (74% of the 65 patients) did not have a stroke.” Dr. Vivek Reddy

Dr. Reddy reported that despite these findings, a majority of Watchman patients with an identified DRT (74% of the 65 patients) did not have a stroke. And in Watchman patients who did have stroke, 87% occurred in the absence of a DRT.

Implications: There is a strong case for rethinking the timing of planned follow-up TEE examinations of Watchman patients. The standard protocol is a TEE at 45 days after placement, when routine anticoagulation usually stops, and then a second TEE 12 months after placement.

Dr. Reddy suggests a better schedule might be to perform the first TEE at 3-4 months after placement when oral anticoagulant therapy stops. This gives time for a potential DRT to form.

What this Means For Those Patients With a Watchman

“Prevention and management of DRT may require that each [Watchman] patient receive a tailored regimen of anticoagulation and surveillance,” said B. De Lurgio, MD, a cardiac electrophysiologist at Emory Healthcare commenting on Reddy’s report.

If you have a Watchman device, you and your EP should discuss “aggressive surveillance” to find any clots on the face of your Watchman. Usually these can be resolved by taking a course of anticoagulants.

If Closing the LAA: An Alternative Occlusion Device

Lariat placement: lasso around opening to LAA

With no metal involved, another occlusion device is the Lariat II noose-like device which is slipped around the LAA. This ‘lasso’ is then tightened, and eventually the tissue dies and shrivels up (like a grape into a raisin).

But there has been a reported problem with the Lariat, too. For more on the Lariat see my article: Alert: Patients with Lariat Device for Left Atrial Appendage Closure.

A Challenge to Install: Compared to the Watchman, the Lariat is more challenging to install and is currently used less often than the Watchman. Not all EPs install and have experience with the Lariat II. You may need to do research to find an EP experienced and good at installing the Lariat. For more about the Lariat, see Lariat II Suture to Close the Left Atrial Appendage.

Watchman Still As Effective As Warfarin

Regarding this DRT data, Dr. Reddy said he didn’t think this data takes away from the argument that the Watchman is a reasonable strategy. “It doesn’t add or detract from the previous data.”

Clots can form on any foreign body as well as inside the heart.

Comparing stroke risks: In cases where no treatment was applied (neither anticoagulants nor the Watchman), the overall ischemic stroke rate is 6.0% per year.

Contrast that 6% rate to the stroke rates of 1.77% per year in people with the Watchman device and 1.71% per year for those on oral anticoagulation.

The Watchman is still a viable option against stroke risk.

Resources for this article
Dukkipati, SR et al. Device-related thrombus after left atrial appendage closure: incidence, predictors, and outcomes. Circulation. 2018; May 11: (Epub ahead of print)

Perriello, B. HRS 2018 Roundup: Device-related blood clots with Boston Scientific’s Watchman implant. May 11, 2018.

Andrew D. Bowser. Device-related thrombus associated with ischemic events. Cardiology News. May 14, 2018.

How Can I Avoid Arterial Calcium Deposits When Taking Coumadin?

Holly Hannula wrote me about being on Coumadin (warfarin) for 12 years because she has a mechanical heart valve. She’s alarmed by a recent scan of her artery walls showing dangerously high calcium deposits, i.e. the amount of hardening of the arteries (atherosclerosis).

Holly’s doctors recommended an angiogram (X-ray) and stents to be put in wherever needed and done very soon. She felt that was too drastic, that her quality of life was good and she was active and social. She and her husband declined those procedures.

Her emailed continued:

“The doctors won’t or can’t change me to a different blood thinner. If I have to take Coumadin for the rest of my life, can I reduce the calcification with vitamin K2 (MK-7)?”

Holly’s coronary artery calcium score is 800 which is dangerously high.

A score between 100 and 399 is classified as increased calcification, and any score over 400 signifies extensive calcium deposits. If your score is over 1,000, you have a 20 percent chance of having a serious or fatal cardiac episode within one year of testing.  (See table below for all scores.)

A score over 1,000 equals a 20% chance of a serious or fatal cardiac event within one year.

No wonder Holly is worried!

What are Her Options?

Because she has a mechanical heart valve, Holly doesn’t have a lot of options. Treatment Guidelines by the American College of Cardiology/American Heart Association (ACC/AHA) only include warfarin (Vitamin K Antagonist) therapy and perhaps aspirin. None of the newer anticoagulants are included.

One might think that a newer anticoagulant like Eliquis would work as well as Coumadin if one has a mechanical valve. But right now, this isn’t a recommended treatment. (For example, the maker of Eliquis states that it isn’t for patients with artificial heart valves.)

My Best Effort for Holly: In my return email, I promised Holly that I would get in touch with Bristol-Myers Squibb, the maker of Eliquis, to see if it could possibly be used in her case.

Tragic Dangers of Warfarin Not Recognized

It’s tragic that Holly has such extensive calcium deposits due to having to take warfarin (Coumadin) which works by blocking Vitamin K.

Vitamin K is essential for heart and bone health. Without enough K-2, osteocalcin, a protein that binds calcium to bone, doesn’t function. Instead the calcium ends up clogging arteries. See Arterial Calcification From Warfarin: Vitamin K May Reverse it.

What’s equally tragic is how few doctors and their patients are aware of this side effect of taking warfarin (Coumadin).

Vitamin K2 Reverses Arterial Calcification!

But, as Holly has already researched and as I described in my article, Arterial Calcification From Warfarin, high doses of Vitamin K2 MK-7 reversed arterial calcification in recent preliminary studies. (MK-7 means the Vitamin K2 also has a Natto component. Natto[kinase] is a known natural blood thinner.)

But what K2 MK-7 dosage should Holly consider? We don’t have enough human research yet to give a definitive answer, but we do have some indications.

Animal research: In an animal study, rats were initially fed a six-week diet of warfarin to induce calcium buildup in blood vessels. Some rats were then fed high dose Vitamin K1 or K2 (MK-4) for six weeks. They not only had no further arterial calcium accumulation but, more importantly, had a 37% reduction of previously accumulated arterial calcification. After 12 weeks, there was an astounding 53% reduction.

Doses: Note the distinction between mg and mcg. 1 mg = 1000 mcg

Mega dose or RDA? In the above study of rats, the human equivalent of the vitamin K2 dose is in the range of  52,000 mcg (52 mg) to 97,000 mcg (97 mg) per day.

Admittedly, these are high doses compared to the standard daily recommend dosages (90 mcg [0.09 mg] for females and 120 mcg [0.12 mg] for males).

Already approved: In Japan, a 45,000 mcg (45 mg) daily dose of the MK-4 form of vitamin K2 is approved as a drug to treat osteoporosis.

Vitamin K and Dosages

Forms of Vitamin K: Consider a high quality MK-7 form of Vitamin K2. Plus, as they are inexpensive, include vitamin K1 and MK-4 to help inhibit and possibly reverse vascular calcification.

Remember to always take your Vitamin K supplement with fatty foods since it is fat-soluble and won’t be absorbed without it.

to avoid arterial calcification

Although the exact dosage of Vitamin K is yet to be determined, one of the world’s top Vitamin K researchers, Dr. Cees Vermeer recommends between 45 mcg and 185 mcg daily for normally healthy adults. LifeExtension magazine recommends 180 mcg.

To Reverse Arterial calcification

To reverse or reduce calcium plaque, you might consider the ultra high doses of 45-50 mg (45,000 mcg) daily, which is based on the research with rats. But only under your doctor’s supervision!

It’s most important that Holly should NOT make any changes to her treatment plan without consulting with her doctor first.

No Overdosing on Vitamin K

You need not worry about overdosing on K2—people who have been given a thousand-fold increase over the recommended dose over the course of three years have shown no adverse reactions (i.e. no increased clotting tendencies).

Advice for Warfarin Users

If you are taking warfarin, your goal should be to maintain the highest healthy levels of Vitamin K to counteract the effects of warfarin on your arterial and bone health.

If you change from warfarin to a NOAC, your goal should be to restore your arterial and bone health from the effects of warfarin by maintaining the highest healthy levels of Vitamin K.

Additional reading about Vitamin K To learn more about the types of Vitamin K, see our article, Vitamin K―Protection Against Arterial Calcification & Cardiovascular Disease

On a personal note: I’ve had a CT scan which revealed calcium deposits in my heart’s arteries, especially in the “widow maker”, the Left Anterior Descending artery (LAD).
After writing this article, I’ve decided to take 45 mg (45,000 mcg) of Vitamin K2 daily.
Coronary Artery Calcium Score Interpretation
 0No identifiable plaque. Risk of coronary artery disease very low (<5%)
 1-10Mild identifiable plaque. Risk of coronary artery disease low (<10%)
 11-100Definite, at least mild atherosclerotic plaque. Mild or minimal coronary narrowings likely.
 101-400Definite, at least moderate atherosclerotic plaque. Mild coronary artery disease highly likely. Significant narrowings possible
 > 400Extensive atherosclerotic plaque. High likelihood of at least one significant coronary narrowing.

Back to Top

Resources for this article
• Goodman, Denonis. The New Nutrient Fix. Bottom Line/Health. July, 2015, p. 3.

• Faloon, William. Turning To Stone. Life Extension Magazine, July 2015, pp. 7-16. Last accessed Aug 10, 2015. URL:

• Tantisattamo E et al. Increased vascular calcification in patients receiving warfarin. Arterioscler Throm Ib Vasc Biol. 2015 Jan;35(1): 237-42. doi: 10.1161/ATVBAHA.114.304392

• Pilkey, RM, et al. Subclinical vitamin K deficiency in hemodialysis patients. Am J Kidney Dis. 2007 Mar;49(3):432-9. Last accessed Aug 10, 2015. URL:

• Schurgers, LJ, et al. Regression of warfarin induced medial elastocalcinosis by high intake of vitamin K in rats. Blood. 2007 Apr 1;109(7):2823-31. Last accessed Aug 10, 2015. URL:

• Westenfeld, R, et al. Effect of vitamin K2 supplementation on fictional vitamin K deficiency in hemodialysis patients: a randomized trial. Am J Kidney Dis. 2012 Feb;59(2):186-95. Last accessed Aug 10, 2015. URL:

• Geleijnse, JM et al. Dietary Intake of Menaquinone Is Associated with a Reduced Risk of Coronary Heart Disease: The Rotterdam Study. The Journal of Nutrition, November 1, 2004, Vol. 134, no. 11. 3100-3105. Last accessed 6/19/2015.

• Vitamin K: How much is too much? Alere/ April 1, 2013. Last accessed Aug. 10, 2015. URL:

• Mercola, J. 10 Important Facts About Vitamin K That You Need to Know., March 24, 2004 Last accessed Aug 10, 2015. URL:

• Mercola, J. New Study Shows Evidence That Vitamin K2 Positively Impacts Inflammation. October 12, 2013.

The Impact of Race on Stroke Risk Among Atrial Fibrillation Patients

It’s well reported that African Americans have a lower risk of developing A-Fib as compared to Caucasians.

But it’s a different story regarding strokes. A new study has found that compared with whites, blacks are at increased risk of developing an ischemic stroke either before or after a diagnosis of atrial fibrillation (A-Fib).

A new University of Pennsylvania study found that such strokes may occur even before the patient is aware of having the heart-rhythm problem, and that this risk is higher for black patients. In many cases, the stroke was the red flag that led to the patient’s A-Fib diagnosis.

African Americans and Heart Disease

Heart disease tends to occur earlier in African American patients than in white counterparts.

The death rate from heart-related causes is higher, too, largely due to a higher rate of heart attacks, sudden cardiac arrest, heart failure, and stroke, according to the American Heart Association

The Penn Study: Looking Back and Monitoring Forward

Researchers used a centralized pool of patient data from across the University of Pennsylvania Health System, which was comprised of 56,835 patients without a history of atrial fibrillation or a remote history of stroke.

Of these patients, the authors identified 3,507 patients who developed A-Fib. Upon diagnosis, they checked each patient’s medical history for the prior six months to document any history of stroke.

Going forward, the authors monitored these A-Fib patients for strokes for a median of 3.6 years.

Unique Design: The study design was unique in that researchers had a time point that represented the initial diagnosis of atrial fibrillation.

This approach provided an opportunity to examine the risk of stroke during a six-month period prior to a formal, clinical diagnosis of atrial fibrillation. Until now, no prior study has examined stroke risk in this period prior to a diagnosis of atrial fibrillation.

Study Findings

Out of 538 strokes occurring in the study periods, nearly half, 254, occurred before diagnosis with atrial fibrillation.

The authors suspect that in many of those 254 cases, the patients already had A-Fib but were undiagnosed.

Blacks had an independently higher risk of stroke both before and after being diagnosed with A-Fib, as compared with whites.­

Prior Six Months Findings: For the strokes that occurred in the six months before A-Fib diagnosis, the rate in black patients was about one-third higher than the rate in white patients.

Findings after A-Fib Diagnosis: For the strokes that occurred in the years following an A-Fib diagnosis, the rate in black patients was two-thirds higher than in white patients — a 2.5 percent chance of stroke per year in black patients compared with a 1.5 percent chance for whites.

Blood-Thinning Medicines: The increased stroke risk for black patients (with A-Fib) was especially high among those who did not have prescriptions for blood-thinning medicines (i.e., warfarin or NOACs).

But even the black patients with prescriptions had a somewhat higher risk of stroke than their white counterparts. (Note: The study authors did not examine whether patients took the medicines, only if they had been given a prescription.)

Editor’s Comments

It’s well reported that African Americans have a lower risk of developing A-Fib as compared to Caucasians. But until now, there was little data on the additional risks that come with A-Fib for each race.

The new findings build on previous studies examining the impact of race on the risk of developing atrial fibrillation.

More Facts About Strokes in African Americans: On his website, Dr. Greg Hall, who specializes in urban health and the clinical care of African Americans shared these sobering facts about strokes in African Americans:

“Most strokes in African Americans occur due to high blood pressure, and a much higher number of African Americans have uncontrolled blood pressure.
quarter of all strokes occur in the presence of atrial fibrillation (a fib). And while representing 13 percent of the US population, African Americans experience almost twice that percentage of all strokes (26%).
Strokes are worse in Blacks. And when a stroke occurs, African Americans have them earlier in life and present with more severe and disabling conditions. “

To learn more, see Dr. Hall’s post: Atrial Fibrillation in African Americans

A-Fib Stroke Risk Greater for Blacks: This is obviously a very important study for black patients. If you’re African American, you have less chance of developing A-Fib. 

Blacks have almost twice the percentage of all strokes (26%) while making up only 13% of the U.S. population.
But if you do develop A-Fib, your stroke risk is much greater than for Caucasians. As Dr. Hall points out, African Americans experience almost twice the percentage of all strokes (26%) while making up only 13% of the U.S. population.

“Silent” A-Fib Stroke Risk Greater for Blacks: An even more disturbing fact is that in this study, half of the strokes occurred before an African American patient was diagnosed with A-Fib. Silent A-Fib is a danger for all A-Fib patients, but the stroke risk was nearly one-third higher in black patients.

Blacks Urgently Need Monitoring for Silent A-Fib: Most strokes in African Americans occur because of high blood pressure which is more prevalent in blacks. But from a public health aspect, it’s even more important to test black patients for silent A-Fib. Monitoring for silent A-Fib needs to become Standard Operating Procedure for blacks reaching middle age.

If you are African American, you should be monitored or get yourself a DIY A-Fib monitor to make sure you don’t have silent A-Fib.

(For recommended DIY heart monitors, see my article, Do-It-Yourself ECG: A Review of Consumer Handheld ECG Monitors.) 

Resources for this article
Patel PJ, et al. Race and stroke in an atrial fibrillation inception cohort: findings from the Penn Atrial Fibrillation Free study [published online February 19, 2018]. Heart Rhythm. doi:10.1016/j.hrthm.2017.11.025.

Avril, T. Black patients with a-fib at higher risk of stroke, Penn study finds, Health/The Inquirer, Daily News, Feb. 20, 2018.

African Americans with Atrial Fibrillation at Significantly Higher Risk for Stroke Compared to Caucasians with the Disease.  Press Release. Article ID: 689679, Released: 16-Feb-2018.

Ischemic Stroke Risk in Atrial Fibrillation Varies by Race. Cardiolog Advisor, February 28, 2018.

Roger VL, Go AS, et al. Heart Disease and Stroke Statistics—2012 Update: A Report From the American Heart Association. Circulation. 2012;125(1):e2-e220. doi:10.1161/CIR.0b013e31823ac046. Strokes in African Americans.  October 22, 2017 by Dr Greg Hall.


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